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Orthodontic arch wires /certified fixed orthodontic courses by Indian dental academy


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Orthodontic arch wires /certified fixed orthodontic courses by Indian dental academy

  1. 1. Orthodontic wires INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Contents Ideal properties of orthodontic wires. Evolution of orthodontic wires. Stainless steel orthodontic wires. Composite wires. Optiflex arch wires.  Multistranded wires. Australian wires.
  3. 3. Strong Resilient Biocompatible Formable Good range Esthetic Criteria of an ideal arch wire Weldable Poor biohost Good springback Low friction
  4. 4. Springback: This is a measure of how far a wire can be deflected without causing permanent deformation. Springback = YS/E
  5. 5. Stiffness or load deflection rate:  This is amount of force required to produce a specific deformation. 1 Stiffness= -----------Springiness
  6. 6. Formability: High formability provides the ability to bend a wire into desired configurations such as loops , coils without fracturing.
  7. 7. Modulus of resilience or stored energy: Resilience represents the energy storage capacity of a wire which is a combination of strength & springiness.
  8. 8. Biocompatibility & Environmental stability: Biocompatibility includes resistance to corrosion & tissue tolerance to elements in the wire. Environmental stability refers to maintainence of desirable properties of the wire for extended periods of time.
  9. 9. Joinability: The ability to attach auxiliaries to orthodontic wires by welding or soldering. Friction: The preferred wire material should produce least friction at the wire/bracket interface.
  10. 10. Evolution of Orthodontic Wires Noble Metal Alloys: In 1860’s Pierre Fauchard introduced gold , platinum,iridium and silver alloys. Esthetically pleasing and good corrosion resistant. Lack flexibility & tensile strength.
  11. 11. Stainless Steel Wires: In 1919, Hauptmeyer introduced stainless steel to dentistry. He first used it to make a prosthesis & called the alloy WIE PLATIN; in German, “ like platinum”. In 1930, Angle used stainless steel for the formation of ligature wire.
  12. 12. In 1937, Stainless steel was considered to be used as an orthodontic arch wire. A.J.Wilcock introduced Australian wires which are round high tensile stainless steel wires.
  13. 13. Advantages: High stiffness High yield strength High resilience Good formability Good joinability Adequate spring back Biocompatible Corrosion resistance Economical
  14. 14. Disadvantages: High modulus of elasticity Frequent activations are required.
  15. 15. Cobalt chromium alloys: In 1960’s originally developed for use in watch springs by an Elgin watch company. They were later marketed by Rocky mountain orthodontics as Elgiloy.
  16. 16. Advantages: Excellent corrosion resistance. Relatively low cost. Good Biocompatibility. Out standing formability in as received condition. Functionally remains active for longer duration if used as a resilient spring. Greater resistance to distortion.
  17. 17. Disadvantages: Higher modulus of elasticity. Lower spring back than stainless steel Has to be heat treated. Soldering is demanding.
  18. 18. Nickel Titanium Alloys: In 1962, William Buchler first alloyed Nitinol at US Naval Ordinance Laboratory , MaryLand . Nitinol- Ni for Nickel, Ti for Titanium, Nol for Naval Ordinance lab. Andresen introduced NiTi containing equal % Nickel & Titanium.
  19. 19. In 1986 two superelastic alloys (Japanese & Chinese) which has active austenitic phase that forms stress induced martensite. In 1990 ’s a neo Sentalloy which is a true active martensitic alloy having SME was introduced. In 1994, copper containing NiTi products having SME were introduced.
  20. 20. Advantages: Lowest force delivery of the four orthodontic wire alloys. Excellent springback in bendings, particularly for super elastic and shape memory alloys.
  21. 21. Disadvantages: Expensive particularly newer products. Second highest arch wire-bracket friction after TMA. Difficult to place permanent bends & cannot bend wire over sharp edge or into complete loop. Wires cannot be soldered & must be joined by mechanical crimping process.
  22. 22. Beta Titanium alloys: In 1980, beta titanium was introduced by Burstone & Gold berg as wrought orthodontic wire. This alloy is also known as titanium molybdenum aluminum. Alpha Titanium: Structurally it is the alpha phase with closely packed hexagonal structure in contrast to beta titanium with a body centered cubic structure.
  23. 23. Advantages: Intermediate force delivery between stainless steel, Elgiloy & Nickel-titanium. Excellent formability Excellent spring back characteristics. Excellent biocompatibility from high titanium content. Disadvantages: Expensive Higher arch wire bracket friction.
  24. 24. Titanium-Niobium wires: In 1995, an esthetic arch wire known as titanium – niobium wire was introduced by Dr.Rohith Sachdeva. Advantages: Ideal finishing wires Less stiff than TMA, formability. Able to maintain low force levels.
  25. 25. Composite wires: Goldberg et al reported the fabrication of fibre reinforced composites. In 1999, Kusy et al patented a method for pultrusion of fibre reinforced composite wire. Composition: In organic fibre + Thermoplastic resin.
  26. 26. Advantages: High elastic recovery. High tensile strength. Excellent formability. Excellent esthetics. Ability to directly bond attachments to these wires.
  27. 27. Optiflex arch wires:  These are esthetic arch wires composed of Silicon di oxide core -provides force or resiliency. Silicon resin middle layer -Adds strength. Nylon outer layer -- Strain resistant.
  28. 28. These wires provide light forces & are used during initial aligning phase. To prevent permanent deformation sharp bends should be avoided.
  29. 29. Stainless steel wires in orthodontics Introduction: Steel is an iron based alloy which contains less than 1.2% of carbon. Chromium (12-30%) - added to steel, the alloy is called stainless steel.
  30. 30. Composition: Iron - 71% Chromium - 18% Nickel - 0.8% Carbon < 1.2% Others Manganese, Nitrogen, Molybdenum
  31. 31. Additions/impurities: Carbon silicon sulphur phosphorus chromium: Resistant to corrosion.
  32. 32. Passivating effect of chromium: When exposed to air , a thin transparent oxide layer formed on the surface protects it against tarnish & corrosion. Nickel: It helps to stabilize at low temperature. Manganese, Nitrogen: Stabilizes the structure.
  33. 33. Molybdenum: Increases corrosion resistance. Pitting resistance equivalent (PRE), evaluate the resistance of the alloy to pitting corrosion based on the content of Cr, Mo, N The higher the PRE value ,the less susceptible the alloy is to pitting corrosion.
  34. 34. Carbon content: Low carbon content corrosion resistance. Silicon: Silicon at low concentration improves resistance to oxidation.
  35. 35. Advantages: High stiffness High yield strength. High resilience. Good formability Good joinability. Adequate springback Bio compatible. Corrosion resistance Economical.
  36. 36. Disadvantages: Soldering is demanding. Lower spring back than Nickel titanium alloys. High modulus of elasticity. More frequent activations are required to maintain the same force levels.
  37. 37. Classification of stainless steel:   1. 2. 3. 4. 5. 6. Classified according to American iron & steel institute system(AISI). Parallels the unified number system (UNS) & the German standards. (DIN). Austenitic steels. Martensitic steels. Ferritic steels. Duplex steels. Precipitation hardenable steels. Manganese containing steels.
  38. 38. Austenitic stainless steel: At temperatures between 9120C & 13940C, a stable form of iron is a face centered cubic structure ((FCC) called Austenite.  18-8 stainless steel Composition: Chromium 18% Nickel 8% Carbon 0.08-0.15%
  39. 39. Most corrosion resistant of all stainless steels.  Austenite has FCC structure which is unstable at room temperature & turns to BCC structure.  If austenizing elements(Ni ,Mn &N) are added, then stability can be maintained.  They are not attached by magnet. 
  40. 40. Advantages of Austenite 1. Greater ductility & ability to undergo more cold work with out breaking. 2. Substantial strengthening during cold working. 3. Greater ease of welding. 4. Increased formability. 5. Ability to readily overcome sensitization.
  41. 41. Applications of Austenite: 1. In orthodontics --- wires, bands, ribbons, hooks bows & springs. 1. In prosthodontics --- partial denture clasps, bars. 2. Generally --- instruments, burs, pliers sterilizers , trays. space maintainers
  42. 42. Sensitization: Loss of corrosion resistance of 18-8 stainless steel, when heated b/n 4000C-9000C(temperature used during soldering & welding ) is called sensitization. This due to precipitation of chromium carbide at grain boundaries.
  43. 43. Stabilization: Introduction of one or two elements that form carbide precipitates in preference to chromium such as niobium. Stainless steels stabilized in this manner are said to be stabilized steels.
  44. 44. Martensitic stainles steel: When austenite (FCC) is cooled very rapidly (quenched) , it will undergo transformation to a body centered tetragonal structure called Martensite.
  45. 45. Corrosion resistance of martensitic stainless steels is less than other types. High strength & hardness. These are used as surgical & cutting instruments because of its high strength & hardness.
  46. 46. Ferritic stainless steel: Pure iron at room temperature has body centered cubic (BCC) structure called ferrite, stable at 9120C. Super ferrites contain 19-30% chromium.
  47. 47. Duplex steels: Consist of combination of austenite & ferrite . Not attracted by magnets. When improperly heat treated, they have a tendency to form a brittle phase (sigma) that diminishes their corrosion resistance.
  48. 48. Precipitation-Hardenable steels: Hardened by heat treatment unlike other stainless steels. Because of its high tensile strength ,used for mini brackets.
  49. 49. Manganese containing steels: Manganese – used as replacement for nickel. Manganese acts by dissolving the really austenizing element , nitrogen.
  50. 50. Multistranded wires These are small diameter stainless steel wires twisted or braided to form large diameter wires. They may be Round based on cross section Rectangular } 3 strands based on no.of strands 6 strands } Braided based on mode of joining strands Twisted }
  51. 51.
  52. 52. Large elastic deflections & apply low forces compared to stainless steel wires Spring back similar to NiTi, but larger compared to stainless steel & beta titanium.
  53. 53. Australian wires These are round high tensile stainless steel wires & were introduced by A.J.Wilcock. These are used during initial aligning phase.
  54. 54. Grades of australian wires: 1. 2. 3. 4. 5. 6. 7. Regular. Regular plus. Special. Special plus. Premium. Premium plus. Supreme.
  55. 55. Higher yield strength of the newer grade wires influence the following properties: Working range, also called as maximum flexibility, spring back of elastic strain: Range ~ YS --------EM
  56. 56. Resiliency: Modulus of resiliency (YS)2 ~ ---------EM
  57. 57. Zero stress relaxation: Ability of the wire to deliver a constant force over long periods when subjected to an external load. Formability: For the same material, greater the resiliency lesser is the formability.
  58. 58. Banding Banding involves the use of thin stainless steel strips called bands that are pinched tightly around the teeth and then cemented to the teeth. It is preferable to band a tooth that requires buccal as well as lingual attachments. Bands are better likely to resist heavy forces as in the case of extraoral devices such as head gears. Steps in banding: Separation of teeth.
  59. 59. Selection of band material. Pinching of the band. Fixing the attachments. Cementation of the band.
  60. 60. Bonding The method of fixing attachments directly over the enamel using adhesive resins is called bonding. The most accepted method is the pretreatment by acid etching technique. This technique was introduced in 1955 by Buonocore. The pretreatment of enamel by acid etch technique helps in the following ways: Enhances the surface energy . Enhances the surface area and porosity.
  61. 61. Advantages of bonding: It is esthetically superior. It is faster to bond than to pinch bands around the teeth. It enables maintenance of better oral hygiene. It is possible to bond on teeth that have aberrant shapes or forms. It might be impossible to band such teeth. Disadvantages of bonding: •Bonded attachments are weaker than banded attachments and hence are more prone to bond failure. • Bonding involves etching of the enamel with an acid which may lead to enamel loss and an increased risk of demineralization. • Enamel fracture can occur during debonding.
  62. 62.
  63. 63.
  64. 64. Brackets Brackets act as handles to transmit the force from the active components to the teeth. Edgewise type of bracket. Ribbon arch brackets. Weldable and bondable brackets.
  65. 65. Metallic brackets ceramic brackets
  66. 66. Buccal tubes
  67. 67. Lingual attachments
  68. 68. Ligature wires lock pins
  69. 69. Elastics and Elastomerics
  70. 70. Elastic chain E –Thread
  71. 71. Springs
  72. 72. Separators
  73. 73. References Orthodontics –the art and science – S.I.bhalajhi. Orthodontic materials -William A.Brantley. Refined Begg for modern times – Dr.Vijay P Jayade. Anusavice,Philip’s ,Science of Dental materials.
  74. 74. Thank you